In some cases, it may be difficult or economically unfeasible to control the environment of an entire building. In such cases, museums can create local environments or microclimates around specific sensitive objects.
This can be achieved by
Choosing the right display case
using silica gel, humidifiers or dehumidifiers where appropriate
monitoring the environment in sealed cases using humidity indicator strips and hygrometers
installing large boxes with thermo-hygrometers or electronic sensors for electronic data logging
When storing items, always close the door and use museum standard enclosures. These act as a physical buffer against unfavourable conditions and create a stable microclimate for the stored items.
Airtight And Constant Humidity (Low Oxygen) Warehouse
Airtight And Constant Humidity (Low Oxygen) Warehouse is used for mildew and insect prevention, constant humidity cleaning, elimination of acidification, oxidation and chemical corrosion and low oxygen fire prevention of cultural relics and collections of organic materials and metal materials, providing long-term preventive protection and storage of the collections.
Temperature and relative humidity are essential elements in the care of collections. Mould, pests, deterioration and warping are just some of the problems that can occur when these factors are not stable and under control.
Plants and animals contain a high proportion of water, so it is not surprising that their products also retain moisture. When materials absorb and retain moisture, they are described as hygroscopic. These materials can and will absorb or release moisture until they reach a state of equilibrium with the surrounding air.
When the surrounding air is very dry, organic materials release some moisture. They become brittle and may shrink, warp, crack or break.
When the surrounding air is humid, the materials absorb some of the moisture in the air. They may swell, wrinkle, warp, change shape or lose strength. Humidity can also cause mould and fungal growth on organic materials.
Low-Oxygen(Constant Humidity) And Clean Warehouse
Inorganic materials such as glass, ceramics, metals and minerals can also be affected by high or low humidity.
When the air is dry, materials containing natural salts may weather. Salts in deteriorated glass, porous ceramics and some geological materials are carried to the surface by moisture (which may enter the pores during periods of higher humidity). The moisture evaporates and the salt crystallises on the surface.
Corrosion of metals
Discolouration of dyes and pigments
Pyrite decay in geological materials
If the humidity of the air changes frequently, hygroscopic materials will repeatedly expand and contract. This can lead to internal stress and damage.
Constant Humidity Showcase
This is particularly problematic in composite objects where different materials have different shrinkage rates. The expansion of one material may force a change in the dimensions of another material, resulting in considerable tension and ultimately damage. Watch out for such damage to items such as drum skins and paintings on wood panels
Moisture can also initiate or accelerate the damaging effects of airborne pollutants and other harmful substances on many museum objects.
Objects themselves are rarely directly affected by temperature. However, fluctuating heat can damage or impair objects in an indirect way.
Uncontrolled temperatures can
Cause changes in humidity, which can damage sensitive objects through RH fluctuations. This is the main reason for controlling temperature.
Accelerate chemical processes and biological activity.
Cause certain materials to expand and contract. This is particularly harmful for composites whose parts expand at different rates.
Affects the comfort of those who use or access the collection.
Low-oxygen(Constant Humidity) And Clean Showcase
The humidity of the air depends on the temperature. If a cubic metre of air can hold 10g of water at 10°C, the same volume can hold more than 30g when the air is heated to 30°C.
When monitoring a museum's environment, it does not make much sense to measure moisture content in grams or absolute humidity.10 Grams of water feels humid at 10°C, but will appear dry at 30°C.
Instead, the museum's environment is measured in terms of relative humidity (RH). This is expressed as a percentage of the maximum amount of water that the air can hold at that temperature.
At 10°C, 10g of water is the maximum amount that the air can hold, so RH is 100%.
At 30°C, 10g is approximately one third of the maximum amount, so RH is approximately 33%.
The relative humidity also changes when the temperature changes, for example after sunset. This principle is one of the most important factors in the environmental control of museums.
